At the other extreme we have full-sized 3.5" internal hard drives kept in external cases. While this is a somewhat portable solution and is just as effective as internal storage (conceptually anyway, I/O speeds will be slower on a USB/FireWire interface), it's still quite bulky. The middle ground between these is a notebook hard drive (or smaller) that's more portable than a 3.5" drive (i.e. will fit in a pocket) and offers more storage than any flash drive. Transcend's StoreJet is just that: it's a wallet-sized 1.8" hard drive available in 20GB and 40GB capacities.